This invention relates to an apparatus for filling pressurized air into a tire mounted on a rim, and more particularly to an air filling apparatus capable of bringing a bead portion of a tire into close contact with a rim just when pressurized air has been filled in the tire mounted on the rim.
An apparatus for filling pressurized air into a tire mounted on a rim has been disclosed, for example, in Japanese Patent Application Publication No. 53-23,563. This disclosed prior art apparatus includes a disc-shaped air-tight plate 1 and an air-tight ring 2 which are coaxially and telescopically movable relative to each other and toward and away from a table 3 as schematically shown in FIG. 1.
In filling pressurized air into a tire (not shown) previously mounted on a rim by the use of this prior art apparatus, the tire with the rim is first arranged on the table 3 such that the rotating axis of the tire is coaxial to the axis of the air-tight ring 2. The air-tight plate 1 and the air-tight ring 2 are then engaged in an air-tight manner with a flange of the rim and a side surface rubber of the tire, respectively, while pressurized air is supplied into the air-tight space 4 formed between the air-tight plate and ring 1 and 2 through a supply tube 5 so that the pressurized air is filled in the internal space in the tire through the clearance between the rim and a bead portion of the tire temporarily for a period of time.
Thereafter, the table is lowered, while the air-tight space 4 is air-tightly maintained until the engagement between the air-tight ring 2 and the side surface rubber of the tire is released, thereby completely filling the pressurized air into the tire. Reference numerals 6 and 7 denote rod members whose ends are connected to the telescopically arranged air-tight plate 1 and ring 2, respectively, and the other ends are connected to conventional cylinders (not shown). The air-tight plate 1 and ring 2 are moved in rotating axial directions of the tire relative to the table 3 individually in response with actuations of the rod members 6 and 7.
With this arrangement of the known apparatus, the end face 8 of the air-tight ring 2 is arranged substantially in parallel with the side surface rubber of the tire arranged on the table 3 or substantially in parallel with a plane perpendicular to the rotating axis of the tire. Therefore, when the table 3 is being lowered, the end face 8 of the air-tight ring 2 is maintained in close contact with the side surface rubber of the tire over the whole its circumference until the end face 8 is disengaged from the side surface rubber of the tire.
Therefore, when the tire is being filled with pressurized air, the whole circumference of the bead portion of the tire must instantaneously get over or ride over the hump of the rim. In other words, it is required to supply a pressurized air of, for example, 4 to 6 kg/cm.sup.2 which is higher than a set pressure of 3 to 5 kg/cm.sup.2 into the air-tight space and hence the internal space of the tire for a predetermined time, in order to overcome the resistance caused when the whole circumference of the bead portion of the tire rides over the hump of the rim instantaneously. Consequently, the bead portion of the tire is expanded or deformed radially outwardly and may be plastically deformed as the case may be. On the other hand, it is actually difficult to disengage the end face of the air-tight ring from the side surface rubber of the tire uniformly over its whole circumference, and further it is impossible to bring the tire bead portion into in close contact with the rim over its whole circumference. Therefore, tires filled with pressurized air having required performances cannot be obtained by the use of the apparatus of the prior art.